August 22, 2013

Fermi Enters Extended Mission After Five Years In Space

Having successfully completed its five-year primary mission, NASA’s Fermi Gamma-ray Space Telescope entered the extended phase of its mission earlier this month – a deeper analysis of the high-energy cosmos that the US space agency hopes will continue through the year 2018.

Fermi, which began the extended phase of its mission on August 11, has given astronomers an increasingly in-depth portrait of such phenomena as supermassive black holes in far-away galaxies during its first half-decade of service.

Perhaps the mission’s crowning achievement thus far was the discovery of giant bubbles extending over 25,000 light-years above and below the plane of our galaxy. Scientists believe that those structures could have formed as the result of past outbursts from the black hole residing in the heart of our galaxy.

Furthermore, the project has provided astronomers with new insight about gamma rays, the most energetic form of light in the universe – shedding new light on rapidly rotating neutron stars known as pulsars in the process.

“As Fermi opens its second act, both the spacecraft and its instruments remain in top-notch condition and the mission is delivering outstanding science,” Dr. Paul Hertz, the director of NASA's astrophysics division in Washington, explained in a statement Wednesday.

NASA called the start of Fermi’s extended phase “a significant step toward the science team's planned goal of a decade of observations,” and a large part of the mission involves the Large Area Telescope (LAT), an instrument capable of scanning the entire sky every three hours.

According to the space agency, the LAT has sharper vision and a wider field of view than any other instrument of its kind. Furthermore, it is also capable of covering a broader energy range than any previously flown telescope.

“As the LAT builds up an increasingly detailed picture of the gamma-ray sky, it simultaneously reveals how dynamic the universe is at these energies,” said Peter Michelson, the instrument's principal investigator and a professor of physics at Stanford University.

In addition, Fermi utilizes a second key instrument, known as the Gamma-ray Burst Monitor (GBM). According to NASA, the GBA can see all parts of the sky at any given time, except for the small region blocked by the Earth. This field of coverage allows Fermi to detect a greater number of gamma-ray bursts – large explosions believed to accompany the birth of new stellar-mass black holes – over a broader energy range than any other mission.

“More than 1,200 gamma-ray bursts, plus 500 flares from our sun and a few hundred flares from highly magnetized neutron stars in our galaxy have been seen by the GBM,” said Fermi principal investigator Bill Paciesas, a senior scientist at the Universities Space Research Association's Science and Technology Institute in Alabama.

The monitor also detected approximately 800 gamma-ray flashes originating from thunderstorms here on Earth. While those outbursts typically only last a few thousandths of a second, their emission ranks among the highest-energy light naturally occurring on our planet, NASA officials explained.

“To build on the mission's success, the team is considering a new observing strategy that would task the LAT to make deeper exposures of the central region of the Milky Way, a realm packed with pulsars and other high-energy sources,” they added. “This area also is expected to be one of the best places to search for gamma-ray signals from dark matter, an elusive substance that neither emits nor absorbs visible light.”